This year, we are seeking to bring our combat robot Troublemaker back from retirement after 10 years of
being out of the arena. The past few months we have
taken the first steps towards reviving the once dormant bot.

We’ve upgraded the long-dead NiCad packs to new LiPoly
packs; and we’ve sketched out new designs for its hobbled
spinning weapon.

This month, we are putting a new spinning weapon
design to the test and taking our beloved combot one step
closer to returning to competition.

Spin Doctor

Last month — sort of like the first half in the concluding
installment of a movie “trilogy” converted into a tetralogy
as part of a cynical money grab — our analysis of
Troublemaker’s existing weapon design might have seemed
like all preamble with no payoff. We promise a destructive
payoff this time, but we think that our experience
demonstrates the value of planning out a good design.

Jumping back into Robot Central with nothing more
than the amorphous goal of making a new weapon would
likely result in a lot of sound and fury signifying nothing.
Without a clear goal, we could have mistakenly cut up
some valuable metal in pursuit of ideas with obvious flaws
that might have been exposed by spending a few minutes
with pen and paper. With our pen and paper session
behind us, we were ready to fire up the power tools.

Last time, we designed some promising candidates to
replace the tethered weights that we used with mixed
success during three years of competition at BotBash. The
tethered weights packed a lot of punch and prevented the
impact force from being transferred into the spinning
mechanism, but the weights would become untethered and
require us to rely on the robot’s front spikes for the rest of
the competition. We designed some alternate ends for the
spinning weapon that wouldn’t have the same weakness.

One design was for a sharp spinning blade. The blade
itself would be connected to the crossbar with one bolt so
that it could rotate between the crossbar supports. Another
design was for hammers that would have some rotation,
but they possessed thicker ends that could not rotate
through the crossbar and would cause the hammer head to
crash into it.

With our design in mind, we headed into Robot Central
to see what kind of materials we had to make it a reality.
The most plentiful varietal of metal we had was 6061
aluminum; 6061 is a fine alloy, but we didn’t think it was
well suited for the weapon.

Many combat robots are armored with 6061 or a
tougher aluminum alloy. The weapon would lack any
intrinsic advantage because of its material – it would likely
be just as hard (or less!) than whatever it was hitting.

Another possibility was 7075 aluminum; 7075 is a
stronger alloy than 6061, and it is what we armored

Troublemaker with. So, 7075 is a great standby, but we
were in the mood for something a little more exotic.
Fortunately, we are loathe to depart with potentially
useful scraps of metal, and a few castoffs from our 30
pounder Twibill Trouble held some promise. Twibill Trouble
is named for the double-bladed battle axe that it resembles.
With no powered weapon, Twibill Trouble relies on its
two side-mounted blades for offense. The blades
themselves are made of chromoly — a steel alloy using
chromium and molybdenum as alloying elements.
The mounts for Twibill Trouble’s blades are made from
1/4 inch thick titanium. Chromaly and titanium would make
perfect business ends for Troublemaker’s improved spinner.
Since the weapons would attach to the ends of the
spinner, we wouldn’t need very large pieces of material to
achieve the shape and reach we envisioned. Even the
Twin Tweaks
by Bryce Woolley and Evan Woolley

How Troublemaker
Got Its Weapon
Back

Go to www.servomagazine.com/index.php/magazine/
article/june2014_Twin Tweaks to comment on this article.

SERVO 06.2014 69

Twin brothers hack whatever’s put in front of them, then tell you about it.